Antifriction gascheck wads



Nov. 10, 1959 H. 5. WHITE 2,911,911

ANTIFRICTION GASCHECK WADS Filed Oct. 6. 1955 r 1 Pg. 4

5 INVENT OR 57 Ham-[2T5 WHITE BY m I 2,911,911 Patented Nov. 10, 1959United States Patent ANTIFRICTION GASCHECK WADS Hobart S. White,Bethesda, Md. Application October 6, 1955, Serial No. 539,035

6Claims. (Cl. 102-38) (Granted under Title 35, US. Code (1952), see.266) The invention described herein may be manufactured and used by orfor the Government of the United States for governmental purposeswithout the payment to me of any royalty thereon, in accordance with theprovisions of 35 United States Code (1952) section 266.

This invention relates to polytetrafiuoroethylene wads suitable in shapeand size for positioning at the base of a projectile before or duringthe operation of seating the projectile in its case.

One object of this invention is to provide a gascheck which willinsulate the base of the projectile from the hot gases of combustion.

Another object of this invention is to provide a seal which will preventleakage of the combustion gases during the firing of a projectile.

Still another object of this invention is to provide means fordepositing particles of a heat resistant lubricant such aspolytetrafluoroethylene in the 'bore of a gun barrel when a projectileis fired, to provide low friction and also to prevent fouling of the gunbore.

The above objects result largely from the behavior characteristicsexhibited by polytetrafiuoroethylene-when used as a gascheck wad,namely; excellent heat insulation and gas sealing ability withoutbreakdown at high pressure and temperature ranges, and low coefiicientof friction.

In particular, in accordance with the principles of this invention it ispossible to fire lead bullets, and lead bullets having conventionalcopper gaschecks, without the necessity of providing a lubricant on thebullets and without the danger of lead-fouling accumulating in the boreof the firearm. With existing ammunition it is necessary to providegrease or other forms of lubricant on lead bullets to preventlead-fouling of the bore, as is well known. It will be apparent that theprinciples of this invention are not limited to lead bullets, but may beapplied to projectiles of all types in general.

Other uses and advantages of the invention will become apparent uponreference to the specification and drawings in which Fig. 1 shows aconventional jacketed projectile-type bullet employing the novelgascheck wad of the instant invention;

Fig. 2 shows a modified form of the gascheck wad of Fig. 1 as used witha conventional boattail-type projectile, and

Figs. 3, 4, and 5 show various modifications of the gascheck wad of theinstant invention as applied to solid projectiles.

The invention in this case is based on the inherent characteristics ofsubstances such as polytetrafiuoroethylene. Such substance, for example,commercially pure Teflon manufactured by E. I. du Pont de Nemours andCompany, exhibits characteristics of excellent heat insulation (poorheat conductivity), gas sealing characteristics at extremely hightemperatures and pressures such as are encountered in the bore of a gunor rifle, and a low coefficient of friction.

The present invention contemplates providing such substance in the formof a gascheck wad of substantially the same diameter of the projectilein sealing engagement with the base of the projectile so that it willtraverse the length of the gun-bore when the projectile is fired.

It has been found that a gascheck of such size and form may readily andinexpensively be associated with the base portion of a projectile sothat when seated within its cartridge case, a unitary assembly includingthe gascheck is produced.

The diameter of the polytetrafiuoroethylene wads is made approximatelythe same as the diameter of the base of the projectiles in themodification where the wads are attached to the base of the projectile,or the diameter may be made slightly larger when a friction fit in theneck of the cartridge case is used to position the wads.

The length of these polytetrafluoroethylene wads is made sufiicient toprevent total decomposition of the wads within the bore of the barrel asthe projectile traverses the bore. In general, the length of thepolytetrafluoroethylene wads should not be less than one fourth thediameter of the projectile, but need not be greater than the diameter ofthe projectile.

The polytetrafluoroethylene employed for the gaschecks is of ordinarycommercial purity as supplied by the E. I. du Pont de Nemours andCompany under the trade name of Teflon. Small amounts of impurities oradulterants are tolerated, but relatively large amounts of adulterants,which might detract from the previously cited desired properties ofpolytetrafluoroethylene, cannot be tolerated within the scope of thisinvention.

Since the polytetrafluoroethylene employed for the gascheck exists as awax-like solid it may be readily shaped and formed and secured to theprojectile in a simple and efiicacious manner as disclosed in thedrawings.

The gascheck is shown in the various embodiments suitable forapplication to a projectile in Figs. l-5. Generally, as indicated it ismade in substantially cylindrical or disc-like form by any convenientmethod such as by molding, extruding or machining.

In its simplest form, the gascheck may be in the form of a simplecylinder 1 as shown in the modification of Fig. l. The gascheck wad 1 isformed to the proper diameter and thickness in accordance with thepreviously described criteria and is then inserted in the neck of thecartridge case 3 between the propellant 4 and the base of the projectile2. In assembling the cartridge, the gascheck is frictionally held inplace and is secured by the subsequent seating of the projectile 2 inthe case 3 in a conventional manner.

The modification shown in Fig. l is particularly adapted for use withjacketed projectiles of the type shown in Fig. 1 where it would bedifiicult or undesirable to interfere with the structure of theprojectile. The gascheck wad shown in Fig. 2 is convenient for the typeof projectile having the boattail shape generally indicated in Fig. 2.Fig. 2 shows a jacketed projectile having a lead body portion 5 and anenclosing jacket 6 of copper alloy or steel as is conventional. Thestandard taper 2a provided on the tailend of such type of projectileprovides a convenient means for securing the gascheck to the projectile.Accordingly, the gascheck 1 in such modification is formed with anannular rim 1a as shown conforming to the taper of the tailend 2a of theprojectile 2. The gascheckis secured to the base of the projectile withan appropriate cement (not shown) and the projectile is then inserted inthe cartridge case as in Fig. '1.

Figs. 3, 4, and 5 show modifications of the gascheck which mayconveniently be employed with solid or lead projectiles. The lack of ajacketing material in such projectiles permitsthe base'to' beconveniently shaped p j tile 2 s houldere o pro d a pro ectin dovetail2b. The gascheck 1 in this modification is oppositely shaped to providea recess or well 111 adapted to register with projection 212.Accordingly, a @Qflvehient means for securing the gascheck to the baseof the projectile is provided by the dovetail engagement between therecess 1b and abutment 2b.

The gascheck 1 shown in the modification of,,Fig. 4 has the sameelementary form as the modification of Fig. 1. In this case a small pin7 or other fastener is employed to stake the gascheck 1 to the base ofthe projectile 2. Such securing means is Pecially suitable for use withlead core projectiles since the pin 7 need only be driven through thewad 1 and intothe..pro-.

V jectile 2.

In the modification shown in Fig. 5 the gascheck 1 has a concentric hole1c such that his attached by friction fit to a mating appendage orconcentric projection 2c at the base of the projectile 2. o

It will be apparent that the embodiments shown are only exemplary andthat various modifications can be made within the scope of invention asdefined in the appended claims.

' What is claimed is:

1. In combination with an ammunition cartridge of the type employing aprojectile and propellant-containing cartridge case, a gascheck wadcomprising a disc of sub.

" covering said base. 7

2. The invention of claiml in which the diameter of saidpolytetrafluoroethylene gascheck wad is slightly larger than thediameter of the projectile whereby said gascheck wad is frictionallyheld in said juxtaposition by frictional engagement with the inner wallof the cartridge case.

71 said p ojectile ewv e dwi h a de ai Pro e and said securingmeahs'comprises a mating recess in said gascheck disc in. whieh. said.projection is seated.

e n ent ne laim 1 in whi said secu means comprises a fastener traversingthe length of said e gflsfiheck disc nd imbedded in the base portion ofsaid iaine e projectile said disc being secured to the base of said Poject le withthe d sc ence a c to and co e the base of said projectileand said tapered wall seating over sa d hea -t iled e s tv ReferencesCited in the file of this pat ent v UNI ED STATES PA EN 4.07.399 18891,031,320 July 2, 19.12 1,944,834 Gerlich Jan. 30, 1934 2 306, 40 422,559 2 5 y 3, '1951 2,6 3,259 -1, V Dec; 22, 1953 2,669g930 Darby Feb.23,1195!!- Z,6? ,,87 Tait 9, 9 2,731,360 ,Love V Jan..17,- 1956 2,82,412" Beeuwkes n, 21, 1958 I I FOREIGN PATENTS 707,065 I 'Great BritainApr. 14, 1954

6. IN COMBINATIONS WITH AN AMMUNITION CARTRIDGE OF THE TYPE EMPLOYING ABOAT-TAILED PROJECTILE, A GASCHECK WARD COMPRISING AN IMPERFORATE DISCMADE OF SUBSTANTIALLY PURE POLYTETRAFLUOROETHYLENE, SAID DISC HAVING ADIAMETER SUBSTANTALLY EQUAL TO THAT OF THE PROJECTILE AND A LENGTHHAVING A RANGE VARYING BETWEEN 1/4 AND THE DIAMETER OF SAID PROJECTILE,AN ANNULAR SHOULDER ON SAID DISC, SAID SHOULDER HAVING AN INERT TAPEREDWALL CONFORMING TO THE TAPER OF THE BOAT-TAILED PORTION OF SAIDPROJECTILE SAID DISC BEING SECURED TO THE BASE OF SAID PROJECTILE WITHTHE DISC CONCENTRIC TO AND COVERING THE BASE OF SAID PROJECTILE AND SAIDTAPERED WALL SEATING OVER SAID BOAT-TAILED PORTION.